Epoxy resin, resin composition, and resin-encapsulated semiconductor device

ABSTRACT

The stilbene epoxy resin having two different aryl groups and an epoxy resin mixture including this stilbene epoxy resin have lower melting points than those of the stilbene epoxy resin having two identical aryl groups and the epoxy resin mixture of the latter stilbene epoxy resin. Compared with the conventional resins, the present resin or resin mixture has improved working and molding properties, which shortens the time required for the molding and working process, resulting in economic advantages and a preferred affect on productivity. The present epoxy resin or resin mixture is preferably used as an adhesive, a coating, an insulating material, an electrical or electronic material for laminated sheets or the like. It is especially suited for use as material for encapsulating electronic parts.

FIELD OF THE INVENTION

The present invention relates to a bisphenol preferably used asadhesive, coating, and electrical or electronic materials such asinsulating materials or laminated sheets or the like, and especially asraw materials or intermediates of electronic parts, as well as to amethod of manufacturing the same.

The present invention also relates to an epoxy resin composition forencapsulating electronic parts and resin-encapsulated semiconductordevice using the same.

BACKGROUND OF THE INVENTION

Transfer molding using an epoxy resin composition is typically adoptedas an economically advantageous means for encapsulating semiconductordevices, such as LSIs, ICs, and transistors.

Recently, resin-encapsulated LSIs are directly soaked in a solder bathfor surface mounting. In the surface mounting process, the encapsulatingmaterial is exposed to a temperature of 200° C. or even higher. Thewater absorbed in the encapsulating material is accordingly expanded andcauses cracks in the encapsulating package of the semiconductor devices.

The epoxy resin encapsulating material is accordingly required to havelow moisture absorption characteristics and improved crackingresistance. A widely used encapsulating material includes glycidyl etherof o-cresol novolak as an epoxy resin and phenol novolak as a curingagent. This widely used encapsulating material must be stored inmoisture-resistant packaging to avoid the above problems. To solve theabove mentioned problems, especially to obtain low moisture absorptioncharacteristics, low viscosity epoxy resins which can contain largeamount of fillers have been developed and used for practicalapplications; for example, a glycidyl ether epoxy resin having atetramethylbiphenyl skeleton.

To improve the physical properties of the encapsulating material, thetechnique of improving the mechanical properties of cured resin iseffective. A known method of improving the mechanical properties ofcured objects of thermosetting resin controls the molecular orientationin the cured objects. There is a prior art document which is related toa stilbene skeleton-containing epoxy resin. It has been reported thatpolymerization of a liquid crystal properties-possessing epoxy compoundin the liquid crystal state in the presence of a small quantity ofcatalyst yields a crosslinked body which retains the liquid crystalstructure and that polymerization in an electric field of specificconditions serves to orientate the liquid crystal domain as seen frompage 182 in the Proceedings of the 3rd Next-generation IndustrialInfrastructure Technology Symposium (1985). In this report, epoxidized4,4'-dihydroxy-&A-cyanostilbene is shown as an example of the compoundhaving liquid crystal properties.

Some epoxy compounds including the rod-like structure of carbon--carbondouble bond, carbon-nitrogen double bond, nitrogen-nitrogen double bond,or the like, which is different from the structure of the presentinvention, have been proposed as compounds possessing excellent physicalproperties in Japanese Patent Laid-open No. S-64-56721 and JapanesePatent Laid-open No. H-1-85215.

A method for manufacturing structural members has been proposed, inwhich the structural members were cured with using a compound having aliquid crystal properties-donating component in the molecular structurethereof, while maintaining the liquid crystal structure, therebyimproving the mechanical properties as seen from U.S. Pat. No.4,762,901, German Patent No. 3,622,613, and Japanese Patent Laid-openNo. S-63-23931. A glycidyl ether of bisphenol compound having anon-substituted or alkyl group-substituted stilbene skeleton, orpreferably having a stilbene skeleton with symmetrically substitutedmethyl groups, is given just as an example of such liquid crystalproperties-containing compounds with other known compounds. Somestilbene bisphenol compounds having identical aryl substituents bound tothe carbon--carbon double bond have also been reported previously.Preparation and physical properties of the compounds, such as4,4'-dihydroxystilbene, 4,4'-dihydroxy-3,3'-dimethylstilbene,4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene, have been disclosed (vonRolf H. Sieber, Liebigs Ann. Chem. 730, 31-46(1969)). A method ofpreparing 4,4'-dihydroxy-&A-methylstilbene has been described inMETHODEN DER ORGANISCHEN CHEMIE (HOUBEN-WEYL) BAND IV/1c Phenol Teil 2P1034.

Epoxy resins having liquid crystal properties or the rod-like structurefor the improved mechanical properties have also been proposed as seenfrom Japanese Patent Laid-open No. H-2-275872. Examples of hydroxylgroup-containing compounds for epoxidation are4,4'-dihydroxy-&A-methylstilbene, 4,4'-dihydroxystilbene,4,4'-dihydroxy-3,3',5,5'-tetrabromostilbene, and4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene. Resin compositions of theepoxy resin having the liquid crystal properties-developing functionalgroup or the rod-like structure and the compound having active hydrogenhave also been proposed for improving the physical properties as seenfrom Japanese Patent Laid-open No. H-4-233933, U.S. Pat. No. 5,292,831,U.S. Pat. No. 5,270,405, U.S. Pat. No. 5,270,404, and U.S. Pat. No.5,266,660. In the specifications of these patents or patent application,orientation of molecules in a cured object with the given epoxy compoundhas been proposed in order to improve the physical properties of thecured object.

Conventional resins for encapsulant, such as, for example, encapsulatingmaterials comprising a glycidyl ether of o-cresol novolak, havesubstantially-balanced heat resistance and molding properties, butpossess poorer physical properties as encapsulant than those of biphenylepoxy resins. The biphenyl epoxy resins have low moisture absorptioncharacteristics and excellent physical properties as the encapsulatingmaterial for surface mounting, but have undesirably low heat resistanceand which results in package cracks under high humidity condition.

The conventional stilbene epoxy resins show excellent curing propertiesbut have high melting points and poorer working properties in theprocess of mixing the epoxy resin component with inorganic fillers or inthe molding process. For example, glycidyl ethers of4,4'-dihydroxystilbene, 4,4'-dihydroxy-3,3'-dimethylstilbene, and4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene have high melting points of208 to 215° C., 150° C., and 151° C., respectively, and suffer fromrather bad working properties. In fact, the epoxy resin of4,4'-dihydroxystilbene can not be used for encapsulating semiconductorsunder the conditions practiced with the current production equipment.

Semiconductor-encapsulating materials including thermosetting resins areformed to packages within a time period of 60 through 90 seconds. Thecured objects of such material have a three-dimensional crosslinkedstructure without any specific molecular orientation as disclosed in theprior art described above. The prior arts above have been proposed tofurther improve the physical properties of cured objects by introducinga specific orientation to the cured structure. To introduce the liquidcrystal state or the specific molecular orientation to cured objects,molding under the specified temperature conditions or external controlof the molding conditions by means of an electric field or magneticfield is required. The cured objects having the specific molecularorientation have different strengths and thermal expansion coefficientsaccording to the direction of molding. When stress is applied in theform of tests, such as the solder heat resistance test after waterabsorption, it is concentrated on specific portions of a package havinglow strength and eventually causes cracks in the package.

The cured object prepared from the resin composition according to thepresent invention is only required to have a cured structure ofsubstantially equivalent to that of the conventional thermosetting epoxyresin composition, and is not a cured object including a specificmolecular orientation and having the deteriorating physical propertiesaccording to the direction.

Another technique to further accelerate the orientation of molecules areproposed in which the epoxy compound having a liquid crystalproperties-developing group is previously reacted with the compoundhaving active hydrogen. This technique heightens the degree ofpolymerization of the resin composition, and accordingly increases themelt viscosity of the resin composition including inorganic fillers,which causes difficulties in the molding process. The present inventiondoes not require any specific pre-reaction of the epoxy component withthe epoxy curing component, and accordingly has no specific curedstructure observed as a result of such pre-reaction.

The conventional stilbene epoxy resin, having a high melting point andlow solubility in an organic solvent, is hardly applied to laminatedsheets, composite material, or coating material.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a stilbene bisphenol asan intermediate of a stilbene epoxy resin having a relatively lowmelting point and favorable solubility in a solvent, as well as a methodof manufacturing such a stilbene bisphenol.

Another object of the present invention is to provide a stilbene epoxyresin having a low melting point and favorable solubility in a solventas well as a method of manufacturing such a stilbene epoxy resin.

Still another object of the present invention is to provide an epoxyresin composition, which is preferably used as a high performanceencapsulating material with high reliability and is easily applicable tothe conventional semiconductor encapsulating equipment and processwithout changing the molding conditions and time and the workingproperties of the conventional epoxy resin.

A still further object is to provide an epoxy resin composition havingexcellent working properties, low moisture absorption characteristics,and favorable heat resistance, and especially possesses high resistanceagainst package cracks without any specific pre-reactions or curingconditions.

The present invention includes a number of embodiments, one which isdirected to a stilbene bisphenol represented by the general formula (1),in which two different aryl groups are bound to a carbon--carbon doublebond, ##STR1## wherein R₁ through R₈ independently represent acyclic orcyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atom orhalogen atoms.

The invention also includes a stilbene epoxy resin represented by thegeneral formula (2), in which two different aryl groups are bound to acarbon--carbon double bond, ##STR2## wherein R₁ through R₈ independentlyrepresent acyclic or cyclic alkyl groups having 1 through 6 carbonatoms, hydrogen atom or halogen atoms.

Another embodiment concerns a bisphenol mixture which comprises, forinstance, a stilbene bisphenol represented by the general formula (1),and a stilbene bisphenol represented by the general formula (3) givenbelow in which two identical aryl groups are bound to a carbon--carbondouble bond, ##STR3## wherein R₉ through R₁₂ independently representacyclic or cyclic alkyl groups having 1 through 6 carbon atoms, hydrogenatom or halogen atoms. The bisphenol mixture can be prepared, forinstance, by the combination of steps comprising conducting adehydrochlorination reaction of a 1,1-bis(hydroxyphenyl)-2-chloroethanederivative, wherein the derivative is obtained by a reaction of two ormore phenols with chloroacetaldehyde in the presence of an acidsubstance, and subjecting the reaction product to a rearrangementreaction in the presence of a basic substance.

A further embodiment is an epoxy resin mixture having a melting point ofnot higher than 150° C. which comprises a stilbene epoxy resinrepresented by formula (2), and a stilbene epoxy resin represented bythe general formula (4) given below in which two identical aryl groupsare bound to a carbon--carbon double bond, ##STR4## wherein R₉ throughR₁₂ independently represent acyclic or cyclic alkyl groups having 1through 6 carbon atoms, hydrogen atom or halogen atoms. The meltviscosity of this epoxy resin mixture is generally not greater than 1poise at 150° C.

Related method embodiments include preparing this epoxy resin mixture bythe combination of steps comprising conducting a dehydrochlorinationreaction of 1,1-bis(hydroxyphenyl-2-chloroethane derivative, which isobtained by a reaction of two or more phenols with chloroacetaldehyde inthe presence of an acid substance, in the presence of a basic substanceto yield a dihydroxystilbene derivative; and reacting thedihydroxystilbene derivative with an epihalohydrin in the presence of abasic substance. Another method embodiment involves preparing the epoxyresin mixture by the combination of steps of preparing a1,1-bis(hydroxyphenyl)-2-chloroethane derivative, which is obtained by areaction of two or more phenols with chloroacetaldehyde in the presenceof an acid substance, and allowing it to react with an epihalohydrin inthe presence of a basic substance. In these methods for preparing anepoxy resin mixture, the phenols can comprise two or more phenolsselected among the group consisting of 2,6-xylenol, 2,4-xylenol,3-methyl-6-t-butylphenol, and 2-methyl-6-t-butylphenol. Moreparticularly, the phenols comprise a mixture of 2,6-xylenol and3-methyl-6-t-butylphenol.

Still further, a curable epoxy resin composition embodiment according tothe present invention comprises the combination of (A) a stilbene epoxyresin in accordance represented by formula (2) or an epoxy resin mixturewhich comprises a mixture of resins represented by general formulas (2)and (4); (B) a phenolic epoxy curing agent; and, optionally, (C) aninorganic filler. The stilbene epoxy resin or epoxy resin mixture canhave a melting point of not higher than 150° C. In a curable epoxy resincomposition, which contains an epoxy component represented by formula(2), R₁ can represent a t-butyl group, and R₅ through R₈ canindependently represent acyclic alkyl groups other than t-butyl group orcyclic alkyl groups having 1 through 6 carbon atoms, hydrogen atoms, orhalogen atoms.

A more specific embodiment of the curable epoxy resin compositioncomprises an epoxy resin mixture of, for instance, a stilbene epoxyresin represented by the general formula (2) which comprises at leastone resin selected from among glycidyl ether compounds of3-t-butyl-2,4'-dihydroxy-3',5',6-trimethylstilbene and3-t-butyl-4,4'-dihydroxy-3',5',6-trimethyl-stilbene; and a stilbeneepoxy resin represented by the general formula (4) which comprises atleast one resin selected from among glycidyl ether compounds of4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene,4,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene,2,2'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, and2,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene.

A cured epoxy resin product is obtained by curing the curable epoxyresin composition.

A resin-encapsulated semiconductor device can be manufactured byencapsulating a semiconductor device (element) with an epoxy resincomposition according to the present invention. The epoxy resincomposition can include at least one inorganic filler.

DETAILED DESCRIPTION OF THE INVENTION

Suitable examples of the substituents R₁ through R₁₂ in the stilbenebisphenols represented by general formulas (1) and (3) and in thestilbene epoxy resins represented by general formulas (2) and (4) in thepresent invention include methyl group, ethyl group, propyl group, butylgroup, amyl group, hexyl group, and cyclohexyl group (including therespective isomers) as well as chlorine atom and bromine atom. Methylgroup, ethyl group, propyl group, and butyl group are particularlypreferred because of the low melt viscosity of products and availabilityof material. By preference, in a stilbene bisphenol represented byformula (1), R₁ can represent t-butyl group, and R₅ through R₈ representindependently acyclic alkyl groups other than t-butyl group, cyclicalkyl groups, hydrogen atoms or halogen atoms. By preference, in astilbene bisphenol represented by formula (2), R₁ can represent at-butyl group, and R₅ through R₈ can represent acyclic alkyl groupsother than t-butyl group, cyclic alkyl groups, hydrogen atoms or halogenatoms.

Suitable examples of the stilbene bisphenol of the present inventionrepresented by general formula (1) given above and having two differentaryl groups bound to a carbon--carbon double bond include3-t-butyl4,4'-dihydroxy-3'-methyl-stilbene,3-t-butyl-4,4'-dihydroxy-5,3'-dimethyl-stilbene,3-t-butyl-4,4'-dihydroxy-3',6-dimethylstilbene,3-t-butyl-4,4'-dihydroxy-5-ethyl-3'-methylstilbene,3-t-butyl-4,4'-dihydroxy-3'-methyl-5-propylstilbene,3-t-butyl-4,4'-dihydroxy-5-butyl-3'-methyl-stilbene,3-t-butyl-4,4'-dihydroxy-5-amyl-3'-methylstilbene,3-t-butyl-4,4'-dihydroxy-5-hexyl-3'-methylstilbene,3-t-butyl-4,4'-dihydroxy-5-cyclohexyl-3'-methylstilbene,3-t-butyl-4,4'-dihydroxy-3',5,5'-trimethyl-stilbene,3-t-butyl-2,4'-dihydroxy-3',5',6-trimethylstilbene,3-t-butyl-4,4'-dihydroxy-3',5',6-trimethylstilbene,3-t-butyl-4,4'-dihydroxy-3',5-dimethyl-5'-propylstilbene, and3-t-butyl-4,4'-dihydroxy-3',6-dimethyl-5'-propylstilbene. Among these,3-t-butyl-4,4'-dihydroxy-3',5,5'-trimethylstilbene,3-t-butyl-2,4'-dihydroxy-3',5',6-trimethylstilbene, and3-t-butyl-4,4'-dihydroxy-3',5',6-trimethylstilbene because of they areeasily synthesized and, perform favorably, and are economical, i.e. alow material cost.

The stilbene epoxy resin of the present invention represented by generalformula (2) and having two different aryl groups bound to acarbon--carbon double bond, includes, for instance, glycidyl ethercompounds of the above bisphenols.

Illustrative of the stilbene bisphenols of the present inventionrepresented by general formula (3) and having two identical aryl groupsbound to a carbon--carbon double bond are, among others,4,4'-dihydroxy-3,3'-dimethylstilbene,3,3'-diethyl-4,4'-dihydroxystilbene,4,4'-dihydroxy-3,3'-dipropylstilbene,3,3'-diamyl-4,4'-dihydroxystilbene, 3,3'-dihexyl-4,4'-dihydroxystilbene,3,3'-dicyclohexyl4,4'-dihydroxystilbene,2,2'-dihydroxy-3,3',5,5'-tetramethylstilbene,4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene,4,4'-dihydroxy-3,3'-di-t-butylstilbene,4,4'-dihydroxy-3,3'-di-t-butyl-5,5'-dimethyl-stilbene,4,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene,2,2'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene,2,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, and4,4'-dihydroxy-3,3',5,5'-tetra-t-butylstilbene. Among these,2,2'-dihydroxy-3,3',5,5'-tetramethylstilbene,4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene,4,4'dihydroxy-3,3'-di-t-butyl-5,5'-dimethylstilbene,4,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethyl-stilbene,2,2'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, and2,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene are preferredbecause they are easily synthesized, perform favorably and areeconomical, i.e., a low material cost.

The stilbene epoxy resin of the present invention represented by generalformula (4) given above and having two identical aryl groups bound to acarbon--carbon double bond, include glycidyl ether compounds of theabove bisphenols.

The intermediate of the stilbene bisphenol of the present invention,that is, 1,1-bis(hydroxyphenyl)-2-chloroethane derivative, is obtainedby the reaction of phenols with chloroacetaldehyde.

Various t-butyl group-containing phenols are available, include, amongothers, 3-methyl-6-t-butylphenol, 2-methyl-6-t-butylphenol,2-t-butylphenol, 2-ethyl-6-t-butylphenol, 2-propyl-6-t-butylphenol,2,6-di-t-butylphenol, 2-isobutyl-6-t-butylphenol,2-amyl-6-t-butylphenol, ((2-amyl-6-t-butyl-phenol)),2-hexyl-6-t-butylphenol, and 2-cyclohexyl-6-t-butylphenol. Among these,3-methyl-6-t-butylphenol and 2-methyl-6-t-butylphenol are preferredbecause of the favorable melting point of final products, availabilityof material, and lower material cost. The phenol need not contain at-butyl group, and examples of these phenols include, for instance,cresol, xylenol, trimethylphenol, tetramethylphenol, methylethylphenol,methylpropylphenol, methylisobutylphenol, methylhexylphenol, andmethylcyclohexylphenol (and their isomers). Xylenol is preferred becauseof its favorable balance of performance and material cost.

Examples of the chloroacetaldehyde used in the present invention includechloroacetaldehyde, aqueos solutions of chloroacetaldehyde, acetals ofchloroacetaldehyde, and trioxane-type trimers of chloroacetaldehyde. Theamount of chloroacetaldehyde used is about 0.8 through about 1.4 moles,or preferably an equivalent mole, with respect to a total 1 mole of thephenols. An amount of chloroacetaldehyde less than this range causes theunreacted phenols to remain in the product, whereas the amount greaterthan this range often leads to polymerization of the product.

The reaction of phenols with chloroacetaldehyde is generally carried outin the presence of an acidic substance. Suitable examples of the acidicsubstance include, among others, inorganic acids, such as fumingsulfuric acid, concentrated sulfuric acid, aqueous sulfuric acid,concentrated hydrochloric acid, hydrogen chloride gas, aqueoushydrochloric acid, and trifluorosulfonic acid; organic acids, such asp-toluenesulfonic acid, chloroacetic acid, trichloroacetic acid, andtrifluoroacetic acid; heteropolyacids; and acidic ion exchange resins.Concentrated sulfuric acid is particularly preferred, because it easilygives high-purity products. The amount of acidic substance used is about0.1 through about 10 moles, and is preferably about 0.5 through about 2moles, with respect to 1 mole of chloroacetaldehyde. The amount ofacidic substance less than this range results in the slow reaction,whereas the amount greater than this range is of no additional effect.

The reaction can be conducted in the presence of a solvent. Suitablesolvents for the reaction include, for instance, hydrocarbons liketoluene and xylene, halogenated hydrocarbons like chlorobenzene, etherslike dioxane and tetrahydrofuran, alcohols like methanol and propanol,non-protic polar solvents like dimethyl sulfoxide, dimethylacetamide,and dimethylformamide, glycols like ethylene glycol and propyleneglycol, and acidic solvents like acetic acid. Acetic acid is especiallypreferred. A single solvent or a mixture of suitable solvents can beused.

The amount of solvent used is 0.1 through 20 times, or preferably 0.5through 10 times, the weight of phenols and chloroacetaldehyde. Theamount of solvent less than this range makes precipitates deposited bythe reaction interfere with smooth stirring, whereas the amount greaterthan this range lowers the yield and is economically disadvantageous.

The acidic substance may be added dropwise to the phenols andchloroacetaldehyde previously dissolved in the solvent, oralternatively, chloroacetaldehyde may be added dropwise to the phenolsand acidic substance in a reaction vessel. The time required for thedropwise addition is generally about 0.5 hours through about 10 hours.The reaction continues for about 3 through about 24 hours after thedropwise addition. The reaction temperature is about -30 through about60° C., and is preferably about -10 through about 40° C. The temperaturelower than this range results in the slow reaction, whereas thetemperature higher than this range significantly increases formation ofimpurities. After the reaction, the deposited precipitates are filteredoff, washed with water, and dried under reduced pressure to yield1,1-bis(hydroxyphenyl)-2-chloroethane derivative as an intermediate.

The intermediate is then subjected to a dehydrochlorination reaction anda rearrangement reaction. The 1,1-bis(hydroxyphenyl)-2-chloroethanederivative obtained is dissolved in a solvent and a basic substance,such as an aqueous solution of sodium hydroxide, is added dropwise tothe solution to complete these reactions. Suitable solvents includehydrocarbons like toluene and xylene, halogenated hydrocarbons likechlorobenzene, ethers like dioxane and tetrahydrofuran, alcohols likemethanol and propanol, non-protic polar solvents like dimethylsulfoxide, dimethylacetamide, and dimethylformamide, glycols likeethylene glycol and propylene glycol, and acidic solvents like aceticacid. Alcohols, such as lower-alkyl alcohols like methanol and propanol,are especially preferred. A single solvent or a mixture of suitablesolvents can be used.

The amount of solvent used is 0.1 through 20 times, or preferably 0.5through 10 times, the weight of 1,1-bis(hydroxyphenyl)-2-chloroethanederivative. The amount of solvent less than this range makes saltsdeposited by the reaction interfere with smooth stirring, whereas theamount greater than this range lowers the yield and is economicallydisadvantageous.

The basic substance used for the reaction may be powder, pellets, or anaqueous solution of sodium hydroxide or potassium hydroxide, although anaqueous solution of sodium hydroxide is preferable because of its easyhandling properties and low material cost. The amount of basic substanceused is 1 through 5 moles, or preferably 1 through 2 moles, with respectto 1 mole of the 1,1-bis(hydroxyphenyl)-2-chloroethane derivative. Theamount of basic substance less than this range causes unreacted materialto remain in the product, whereas the amount greater than this range isof no additional effect.

The basic substance may be added dropwise to the1,1-bis(hydroxyphenyl)-2-chloroethane derivative previously dissolved inthe solvent, or alternatively, powder, solution or slurry of the1,1-bis(hydroxyphenyl)-2-chloroethane derivative may be added dropwiseto the basic substance ((phenols and acidic acid)) in a reaction vessel.The time required for the dropwise addition is generally about 0.5 hoursthrough about 10 hours. The reaction continues for about 3 through about24 hours after the dropwise addition. The reaction temperature is about-20 through about 150° C., and preferably about 20 through about 100° C.A temperature lower than this range can result in a slow reaction,whereas a temperature higher than this range is of no additional effect.

After the reaction, the reaction system is neutralized prior to removalof the solvent. Water is added to the reaction vessel after the removalof solvent, so as to allow crystallization of the reaction mixture. Theprecipitates obtained are filtered off, washed with water, and driedunder reduced pressure to yield a bisphenol compound having a stilbeneskeleton.

A bisphenol mixture of the present invention may be prepared by mixingtwo or more bisphenol compounds separately synthesized with one another,or separately synthesizing intermediates obtained in the middle of themanufacturing process of bisphenol compounds and mixing theintermediates prior to completion of the residual reaction.

The stilbene epoxy resin of the present invention is obtained throughthe known process of glycidyl etherification of the stilbene bisphenolgiven above. The known process makes the bisphenol react with anepihalohydrin in the presence of an alkali, such as sodium hydroxide. Inorder to give high-purity products, non-protic solvents and othersolvents like dioxane are preferably used as disclosed in JapanesePatent Laid-open No. S-60-31517, the complete disclosure of which isincorporated herein by reference.

Suitable epihalohydrin useful in the epoxidation reaction includeepichlorohydrin and epibromohydrin, although epichlorohydrin ispreferred because of its availability and low material cost.

Preferred examples of the basic substance used in this reaction include,by way of example, alkali metal hydroxides like sodium hydroxide andpotassium hydroxide. A preferred amount of basic substance used is anequivalent mole with respect to 1 mole of the phenolic hydroxyl group.

Using a lower amount of basic substance is desired. It results in theremaining hydrolytic chlorine. Lesser amounts of gel by-product areobtained which is advantageous from a manufacturing perspective. Incontrast, using a greater amount of basic substance increases the amountof gel by-product and is therefore disadvantageous in the manufacturingprocess.

Solvents applicable to the reaction include, though not limited,non-protic polar solvents like dimethyl sulfoxide, dimethyl sulfone,dimethylformamide, dimethylacetamide, and tetramethylurea, and etherslike dioxane and tetrahydrofuran. A preferred amount of solvent is about5 through about 60 parts by weight with respect to 100 parts by weightof epihalohydrin. An amount less than about 5 parts by weight does notexert the effects of the present invention, whereas a greater amountallows the intermolecular reaction to proceed which can lower thequality of the products.

The amount of epihalohydrin used is preferably about 2.5 through about20 moles or more specifically about 4 through about 12 moles withrespect to 1 mole of the phenolic hydroxyl group. The amount less thanthis range allows the intermolecular reaction to proceed, therebylowering the quality of products, whereas the amount greater than thisrange lowers the yield and is disadvantageous from the industrialviewpoint.

The epoxidation reaction is implemented by dissolving or suspending thestilbene bisphenol derivative in a solution mixture of epihalohydrin andreaction solvent and further adding the basic substance to the solutionwith stirring. The reaction is generally carried out under reducedpressure. The reaction solution is subjected to an azeotropic processwhile the reaction temperature is kept in a range of about 30 to about80° C. The volatile matter is condensed, the condensed solution thusobtained is subjected to an oil-water separation, the oil substance isreturned to the reaction system, and the water is removed. The basicsubstance is added in limited amounts either separately or continuouslyover a period of about 2 through about 10 hours for the homogeneousreaction. Introducing the basic substance in one shot can cause thereaction to proceed locally and unfavorably gives a gel. Aftercompletion of the reaction, unreacted epihalohydrin and solvent areremoved by distillation, and the residue is dissolved in a solventseparable from water, for example, methyl isobutyl ketone, for removalof insoluble inorganic salts. The solution is further washed with waterto remove inorganic component(s) and the remaining polar solvent, anddistilled to remove the remaining solvent to yield a final epoxyproduct.

The stilbene epoxy resin of the present invention may alternatively beobtained through simultaneous rearrangement reaction and epoxidationreaction of the 1,1-bis(hydroxyphenyl)-2-chloroethane derivative.

In this process, the preferable amount of the basic substance used is(an equivalent mole with respect to 1 mole of the phenolic hydroxylgroup)+(an equivalent mole with respect to 1 mole of the hydrolyticchlorine). Since the 1,1-bis(hydroxyphenyl)-2-chloroethane derivativehas two hydroxyl groups and one hydrolytic chlorine atom per molecule,three moles of the basic substance are preferably used with respect to 1mole of the 1,1-bis(hydroxyphenyl)-2-chloroethane derivative. The lessamount of basic substance results in the remaining hydrolytic chlorine,while giving a less amount of gel as a by-product and being thusadvantageous in the manufacturing process. The greater amount of basicsubstance, on the other hand, increases the amount of gel and is thusdisadvantageous in the manufacturing process. The essential conditionsof epoxidation reaction are identical with those specified above.

A mixture of the epoxy resin represented by general formula (2) and thatrepresented by general formula (4) according to the present inventionmay be prepared by mixing separately synthesized epoxy resins with oneanother, or separately synthesizing intermediates obtained in the middleof the epoxidation process and mixing the intermediates prior tocompletion of the residual epoxidation reaction.

In the process of synthesizing the stilbene phenol represented bygeneral formula (1) as a material of epoxy resin, the stilbene phenolrepresented by general formula (3) is formed with the stilbene phenol ofgeneral formula (1). For example, a mixture of stilbene phenols havingthree different basic skeletons X--CH═CH--X, X--CH═CH--Y, andY--CH═CH--Y are synthesized from two different phenols X and Y used asstarting materials.

The stilbene epoxy resin represented by general formula (2) and havingtwo different aryl groups bound to a carbon--carbon double bond isderived from the stilbene phenol of X--CH═CH--Y, where the benzene ringslinked with the carbon--carbon double bond have different substituentsat different positions. The epoxy resin according to the presentinvention is required to include the epoxy resin represented by generalformula (2). The epoxy resin containing only that represented by generalformula (2) is obtained by isolating X--CH═CH--Y from the mixture ofstilbene phenols and glycidyl etherifying the stilbene phenolX--CH═CH--Y. An epoxy resin having a sufficiently low melting point andimproved working properties can not be obtained by simply mixing epoxyresins derived from the stilbene phenols of X--CH═CH--X and Y--CH═CH--Y.

Combination of three or more phenols as starting materials gives asimilar mixture of stilbene phenols. For example, three differentphenols X, Y, and Z give a mixture of stilbene phenols having differentbasic skeletons of X--CH═CH--X, X--CH═CH--Y, X--CH═CH--Z, Y--CH═CH--Y,Y--CH═CH--Z, and Z--CH═CH--Z. The epoxy resin according to the presentinvention is required to include at least one of the epoxy resinsderived from the stilbene phenols of X--CH═CH--Y, X--CH═CH--Z, andY--CH═CH--Z. Starting materials of four or more phenols give similarmixtures.

The epoxy resin according to the present invention can include just oneor more epoxy resins represented by general formula (2), oralternatively includes one or more epoxy resins represented by generalformula (4) in addition to one or more epoxy resins represented bygeneral formula (2). In a mixture of (A) one or a plurality of epoxyresins of general formula (2) and (B) one or a plurality of epoxy resinsof general formula (4), the amount of the component (A) is generally notless than 1% by weight, or preferably not less than 10% by weight, withrespect to the total weight of the components (A) and (B). The lesscontent of the component (A) increases the melting point of theresulting epoxy resin and deteriorates the working properties in themixing process with another component. The content of the component (A)is increased to give epoxy resins required to have a lower melting pointand decreased to give epoxy resins required to have a higher meltingpoint. In the process of the present invention, the component (A) andthe component (B) may be synthesized separately and then mixed with eachother.

The epoxy resin composition of the present invention may include theabove stilbene epoxy resin together with another known epoxy resin.Known epoxy resins applicable for the epoxy resin composition include,for example, glycidyl ether compounds derived from divalent phenols,such as bisphenol A, bisphenol F, hydroquinone, resorcinol,dihydroxynaphthalene, bis(4-hydroxyphenyl) menthane,bis(4-hydroxyphenyl)dicyclopentane, 4,4'-dihydroxybenzophenone,bis(4-hydroxyphenyl) ether, bis(4-hydroxy-3-methylphenyl) ether,bis(3,5-dimethyl-4-hydroxyphenyl) ether, bis(4-hydroxyphenyl) sulfide,bis(4-hydroxy-3-methylphenyl) sulfide, bis(3,5-dimethyl4-hydroxyphenyl)sulfide, bis(4-hydroxyphenyl) sulfone, bis(4-hydroxy-3-methylphenyl)sulfone, bis(3,5-dimethyl-4-hydroxyphenyl) sulfone,1,1-bis(4-hydroxyphenyl)cyclohexane,1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane,1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane,4,4'-dihydroxybiphenyl, 4,4'-dihydroxy-3,3',5,5'-tetramethylbiphenyl,bis(hydroxynaphthyl)methane, 1,1'-binaphthol, and1,1'-bis(3-t-butyl-6-methyl-4-hydroxyphenyl)butane; diglycidyl ethercompounds derived from halogenated bisphenols, such astetrabromobisphenol A; polyphenol and polynaphthol novolak resinsobtained as reaction products of phenols, such as phenol, o-cresol, andcatechol, or naphthols, such as hydroxynaphthalene anddihydroxynaphthalene, with aldehydes, such as formaldehyde; tritylskeleton-containing polyphenols obtained by condensation of phenols,such as phenol, cresol, and methyl-t-butylphenol, and aromaticaldehydes, such as hydroxybenzaldehyde; trityl skeleton-containingpolyphenol novolaks obtained as reaction products of tritylskeleton-containing polyphenols with formaldehyde or the like;polyaralkylphenol resins and polyaralkylnaththol resins obtained asreaction products of phenols, such as phenol, o-cresol, and catechol, ornaphthols, such as hydroxynaphthalene and dihydroxynaphthalene, withxylylene dichloride, bis(hydroxymethyl)benzene, or the like; alicyclichydrocarbon-containing polyphenol resins and polynaththol resinsobtained as reaction products of phenols, such as phenol, o-cresol, andcatechol, or naphthols, such as hydroxynaphthalene anddihydroxynaphthalene, with unsaturated alicyclic hydrocarbons, such asdicyclopentadiene and limonene; alicyclic hydrocarbon-containingpolyphenol novolak resins and polynaththol novolak resins obtained asreaction products of alicyclic hydrocarbon containing polyphenol resinsor polynaththol resins with formaldehyde or the like; glycidyl ethercompounds of polyvalent phenols and polyvalent naphthols obtained bycondensation reaction of phenols or naphthols with aromatic carbonylcompounds; glycidyl ether compounds derived from trivalent or highermultivalent phenols including as a fundamental skeleton fluoroglycine,tris(4-hydroxyphenyl)methane, 1,1,2,2,-tetrakis(4-hydroxyphenyl)ethane,1,3-bis bis(4-hydroxyphenyl)methyl!benzene, 1,4-bisbis(4-hydroxyphenyl)methyl!benzene, or the like and cyclic phenols, suchas calixarene.

The known epoxy resins also include amine epoxy resins derived fromp-aminophenol, m-aminophenol, 4-amino-m-cresol, 6-amino-m-cresol,4,4'-diaminodiphenylmethane, 3,3'-diaminodiphenylmethane,4,4'-diaminodiphenyl ether, 3,4'-diaminodiphenyl ether,1,4-bis(4-aminophenoxy)benzene, 1,4-bis(3-aminophenoxy)benzene,1,3-bis(4-aminophenoxy)benzene, 1,3-bis(3-aminophenoxy)benzene,2,2-bis(4-aminophenoxyphenyl)propane, p-phenylenediaminde,m-phenylenediaminde, 2,4-toluenediaminde, 2,6-toluenediamine,p-xylylenediamine, m-xylylenediamine, 1,4-cyclohexanebis(methylamine),1,3-cyclohexanebis(methylamine), and N,N-diglycidylaniline; glycidylester compounds derived from aromatic carboxylic acids, such asp-oxybenzoic acid, m-oxybenzoic acid, terephthalic acid, and isophthalicacid; hydantoin epoxy compounds derived from 5,5-dimethylhydantoin orthe like; alicyclic epoxy resins, such as2,2-bis(3,4-epoxycyclohexyl)propane, 2,2-bis4-(2,3-epoxypropyl)cyclohexyl!propane, vinylcyclohexene dioxide,3,4-epoxycyclohexyl methyl-3,4-epoxycyclohexane carboxylate; andaliphatic epoxy resins obtained by oxidation of the double bond includedin unsaturated hydrocarbons, such as polybutadiene. One or a mixture ofthese epoxy resins may be included in the epoxy resin composition.

Suitable phenolic epoxy curing agents include, among others, polyphenoland polynaphthol novolak resins obtained as reaction products ofphenols, such as phenol, o-cresol, and catechol, or naphthols, such ashydroxynaphthalene and dihydroxynaphthalene, with aldehydes, such asformaldehyde; trityl skeleton-containing polyphenols obtained bycondensation of phenols, such as phenol, cresol, andmethyl-t-butylphenol, and aromatic aldehydes, such ashydroxybenzaldehyde; trityl skeleton-containing polyphenol novolaksobtained as reaction products of trityl skeleton-containing polyphenolswith formaldehyde or the like; polyaralkylphenol resins andpolyaralkylnaththol resins obtained as reaction products of phenols,such as phenol, o-cresol, and catechol, or naphthols, such ashydroxynaphthalene and dihydroxynaphthalene, with xylylene dichloride,bis(hydroxymethyl)benzene, or the like; alicyclic hydrocarbon-containingpolyphenol resins and polynaththol resins obtained as reaction productsof phenols, such as phenol, o-cresol, and catechol, or naphthols, suchas hydroxynaphthalene and dihydroxynaphthalene, with unsaturatedalicyclic hydrocarbons, such as dicyclopentadiene and limonene;alicyclic hydrocarbon-containing polyphenol novolak resins andpolynaththol novolak resins obtained as reaction products of alicyclichydrocarbon-containing polyphenol resins or polynaththol resins withformaldehyde or the like; trivalent or higher multivalent phenolsincluding as a fundamental skeleton fluoroglycine,tris(4-hydroxyphenyl)methane, 1,1,2,2,-tetrakis(4-hydroxyphenyl)ethane,1,3-bis bis(4-hydroxyphenyl)methyl!benzene, 1,4-bisbis(4-hydroxyphenyl)methyl!benzene, or the like; and cyclic phenols,such as calixarene. Preferred curing agents are phenol novolak resins,naphthol novolak resins, phenol aralkyl resins, naphthol aralkyl resins,trityl skeleton-containing polyphenols, trityl skeleton-containingpolyphenol novolaks, alicyclic hydrocarbon-containing polyphenol resins,and alicyclic hydrocarbon-containing polynaththol resins because oftheir favorable curing properties and moisture resistance. The epoxycuring agent can comprise a single suitable compound or a mixture ofsuitable compounds.

In the curable epoxy resin composition, the phenolic epoxy curing agent(B) can, for instance, be comprised of a polyphenol resin having a meltviscosity of 1.5 poise or less at 150° C. An exemplary polyphenol resincan be represented by the general formula (5) ##STR5## wherein Xrepresents single bond or methylene, Q represents phenylene or adivalent alicyclic moiety derived from dicyclopentadiene or limonene,and n represents an integer of 1 to 20, preferably 1 to 10. The phenolicepoxy curing agent (B) can further comprise a phenol novolak. Exemplarydivalent alicyclic moieties derived from dicyclopentadiene or limoneneare specifically shown as below: ##STR6##

Divalent bisphenols may further be added according to the requirements.Examples of the applicable bisphenol include: divalent phenols, such asbisphenol A, bisphenol F, hydroquinone, resorcinol,dihydroxynaphthalene, bis(4-hydroxyphenyl)ethane,bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)butane,bis(4-hydroxyphenyl)pentane, bis(4-hydroxyphenyl)hexane,1,3,3-trimethyl-1-m-hydroxyphenylindan-5-or-7-ol,bis(4-hydroxyphenyl)menthane, bis(4-hydroxyphenyl)dicyclopentane,4,4'-dihydroxybenzophenone, bis(4-hydroxyphenyl) ether,bis(4-hydroxy-3-methylphenyl) ether, bis(3,5-dimethyl-4-hydroxyphenyl)ether, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxy-3-methylphenyl)sulfide, bis(3,5-dimethyl-4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxy-3-methylphenyl) sulphone,bis(3,5-dimethyl-4-hydroxyphenyl) sulfone,1,1-bis(4-hydroxyphenyl)cyclohexane,1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane,1,1-bis(3,5-dimethyl-4-hydroxyphenyl)cyclohexane,4,4'-dihydroxybiphenyl, 4,4'-dihydroxy-3,3',5,5'-tetramethylbiphenyl,bis(hydroxynaphthyl)methane, 1,1'-binaphthol, and1,1'-bis(3-t-butyl-6-methyl-4-hydroxyphenyl)butane; and halogenatedbisphenols, such as tetrabromobisphenol A.

Other than the above phenols, the following compounds may also be added,depending on the application requirements, polycarboxylic acids, such asmaleic acid, phthalic acid, nadic acid, methyl-tetrahydrophthalic acid,and methyinadic acid, and anhydrides thereof; polyamines, such asdiaminodiphenylmethane, diaminodiphenyl sulfone, diaminodiphenyl ether,phenylenediamine, diaminodicyclohexylmethane, xylylenediamine,toluenediamine, diaminocyclohexane, dichloro-diaminodiphenylmehtane(including their isomers), ethylenediamine, and hexamethylenediamine;and active hydrogen-containing compounds capable of reacting with theepoxy group, such as dicyandiamide and tetramethylguanidine.

The content of the epoxy curing agent is preferably about 0.7 throughabout 1.2 times the weight of the epoxy resin, or more specifically anequivalent weight to that of the epoxy resin. An extreme shift from theequivalent composition results in lowering the moisture resistance andcuring properties.

In the process of curing the epoxy resin composition of the presentinvention, a known curing accelerator may be added. Suitable applicablecuring accelerators include, for instance, organophosphine compounds,such as triphenylphosphine, tri-4-methylphenylphosphine,tri-4-methoxyphenylphosphine, tributylphosphine, trioctylphosphine, andtri-2-cyanoethylphosphine, and their tetraphenylborates; tertiaryamines, such as tributylamine, triethylamine,1,8-diazabicyclo(5,4,0)-7-undecene, and triamylamine; quaternaryammonium salts, such as benzyltrimethylammonium chloride,benzyltrimethylammonium hydroxide, and triethylammoniumtetraphenylborate; and imidazoles. Because of their favorable moistureresistance and curing properties, organophosphine compounds,1,8-diazabicyclo(5,4,0)-7-undecene, and imidazoles, especiallytriphenylphosphine, are preferred.

The epoxy resin compositions according to the present invention canfurther comprise, optionally, inorganic fillers as a component (C).Suitable inorganic fillers include, for instance, silica, alumina,titanium white, aluminum hydroxide, talc, clay, or glass fibers. Silicaand alumina are particularly preferred examples. The inorganic fillersused may be a bulky mixture of different shapes (spherical and ground)and sizes. The content of inorganic fillers is required to be about 25through about 95% by weight with respect to the total weight of theresin composition, and is preferably about 70 through about 95% byweight, although most preferably it is about 80 through about 95% byweight. The content of inorganic fillers less than about 80% by weightresults in poor moisture resistance, whereas that greater than about 95%by weight deteriorates the molding properties.

The spherical powder may be approximately spheres in shape possessing noacute vertices and having the aspect ratio of about 1.0 through about1.2. Preferably used is spherical powder having the spherical degreesimilar to that of commercially available silica powder prepared byflame spraying or sol-gel method, where that substantially close to thetrue sphere is especially preferable. When the standard sphericalprocess is not applicable, spherical powder may be prepared by makingfinely ground particles mixed with a binder spherical by amechanochemical approach.

The ground particles may be polyhedrons or bodies of any other irregularshapes possessing vertices. Ground particles of noncrystalline orcrystalline quartz obtained by grinding synthetic or natural quartzblock are preferable; for example, ground molten silica.

Although any spherical powder is applicable to the present invention, apreferred example including three components x, y, and z is described asfollows. The x, y, and z components respectively have the averageparticle diameter of not less than about 0.1 μm and not greater thanabout 1.5 μm, not less than about 2 μm and not greater than about 15 μm,and not less than about 20 μm and not greater than about 70 μm, or morepreferably having the average particle diameter of not less than about0.1 μm and not greater than about 1.0 μm, not less than about 2 μm andnot greater than about 10 μm, and not less than about 20 μm and notgreater than about 50 μm. Powder having the average particle diameter ofless than about 0.1 μm causes aggregation of particles, which interfereswith homogeneous dispersion into the resin composition and may damagethe flow properties. On the other hand, powder having the averageparticle diameter of greater than about 70 μm can not be easily chargedinto the fine portions of semiconductor elements. The x, y, and zcomponents having the average particle diameter out of the respectiveranges deteriorate the flow properties of the resin composition. Thespherical powder used in the present invention preferably has a narrowervariance of particle diameter, or more specifically a single variance.Therefore using a classification process is preferred in order to selectparticles having substantially uniform particle diameters for all the x,y, and z components. The average particle diameter here is defined asthe particle diameter value under the condition of about 50% weightcumulation when the distribution of particle diameter is measured with aparticle size distribution measuring apparatus, for example, a laserscattering granulometer.

The volume ratios of the spherical powdery components x, y, and z withrespect to the calculated total volume of the x, y, and z components arepreferably not less than about 10% by volume and not greater than about24% by volume, not less than about 0.1% by volume and not greater thanabout 66% by volume, and not less than about 24% by volume and notgreater than about 76% by volume, more preferably not less than about10% by volume and not greater than about 24% by volume, not less thanabout 0.1% by volume and not greater than about 36% by volume, and notless than about 57% by volume and not greater than about 76% by volume,or most preferably not less than about 10% by volume and not greaterthan about 20% by volume, not less than about 4% by volume and notgreater than about 30% by volume, and not less than 60% by volume andnot greater than about 76% by volume. The volume ratios out of theseranges lower the flow properties of the resulting resin composition.

The values of `% by volume` in the present invention are calculatedusing the quotients obtained by dividing the respective weights of thex, y, and z components by their true specific gravities as volumes ofthe respective components.

In general, the apparent volume of particles having a certain particlediameter distribution is varied by the filling conditions of particlesin a measuring vessel and before and after the process of mixingdifferent sets of particles. In the description above, the apparentvolume is thus not used for the calculation of `% by volume` of eachcomponent or set of particles.

The ground particles (component m) used in the present invention have anaverage particle diameter of not less than about 1 μm and not greaterthan about 70 μm, or preferably not less than about 1 μm and not greaterthan about 30 μm. A preferred ratio of the weight of the groundparticles (component m) to the total weight of the component ofspherical powder and the component m of ground particles is not lessthan about 1% by weight and not greater than about 30% by weight. Thecontent less than this range does not have sufficient effects ofreducing fins and flashes (thin resin films formed by the leaked resinsubstance) formed according to the properties of resin and the shapes ofthe encapsulating device and molding device used. The content exceedingthis range, on the other hand, lowers the flow properties of theresulting resin composition.

It is preferable that the fillers used in the present invention aresufficiently mixed and blended in advance. According to a concreteprocedure, the fillers are blended with a device utilizing rotors or theair, such as a mixer or a Ko-kneader, or a device for vibrating,shaking, or rotating a vessel with the fillers set therein. In order todetermine whether the fillers are sufficiently kneaded, particle sizedistributions are measured for samples from different positions andcompared with one another for identification. The fillers may bepre-treated with a coupling agent or resin according to therequirements. One applicable method of pre-treatment mixes a couplingagent or resin with the fillers in a solvent and subsequently removesthe solvent. Another method directly mixes a coupling agent or resinwith the fillers by means of a blender.

Natural wax, synthetic wax, higher fatty acids and their metal salts,parting agents like paraffin, coloring agents like carbon black, andfinishing agents like silane coupling agents may further be added to thecomposition of the present invention. Flame-retardants, such as fillerslike antimony trioxide, or phosphorus compounds or brominated epoxyresins, may also be added. Brominated epoxy resins are especiallypreferable for obtaining flame-retarding effects.

A variety of non-reacted or reacted elastomers may be added in order tolower the stress. Suitable non-reacted or reacted elastomers include,for instance, polybutadiene, butadiene-acrylonitrile copolymer, siliconerubber, and silicone oil.

Resin compositions according to the present invention can be used forencapsulating semi-conductors or other electronic parts the resultantresin-encapsulated semiconductor devices are prepared using a knownmolding process, such as transfer molding, compression molding, orinjection molding.

Resin compositions according to the present invention are described inJapanese Application 07-108418 filed May 2, 1995, Japanese Application07-106769 filed Apr. 28, 1995, Japanese Application 07-106768 filed Apr.28, 1995, and Japanese Application 07-104464 filed Apr. 27, 1995, thecomplete disclosures of which are incorporated herein by reference.

EXAMPLES

Examples of the present invention are given below, although theinvention is not restricted in any sense to these examples.

In the description below, the epoxy equivalent weight is defined by themolecular weight of epoxy resin per epoxy group.

The quantity of hydrolytic chlorine expressed by ppm was measured bydissolving the epoxy resin in dioxane, adding an alcohol solution ofpotassium hydroxide to the resin solution, heating the resin solutionfor 30 minutes under reflux, and measuring the quantity of chlorine ionsreleased from the resin solution by back titration with an aqueoussolution of silver nitrate.

Properties of the kneaded substances and cured objects were evaluatedaccording to the following methods.

Working properties: The working properties in the mixing process ofkneading the resin component, inorganic fillers, and other additiveswere evaluated using Reference 3 as a standard. Open circles (o)represent equivalent working properties to those of Reference 3 andcrosses (x) represent poor working properties having difficulty inpreparation of homogeneous material.

Barcol hardness: The Barcol hardness was measured under the condition of175° C./90 sec with a model-935 hardness tester according to ASTM D-648.

Glass transition temperature: The glass transition temperature wasmeasured with a heat mechanical analyzer (SHIMADZU DT-30).

Bending strength, Bending modulus: The bending strength and the bendingmodulus were measured with a tensile machine (SHIMADZU IS-10T) accordingto JIS K-6911.

Water absorption: The variation in weight was measured under thecondition of 85° C./85%RH with a constant-temperature, constant-humiditybath (Advantec TOYO AGX-326).

Spiral flow: The spiral flow was measured under the condition of 175°C./70 kg/cm2 in conformity with EMMI-1-66.

Solder cracking: Simulated ICs (52-pin QFD packaging: thickness inpackaging=2.05 mm) were exposed to the moisture under the condition of85° C./85%RH and then soaked in a solder bath of 240° C. for 30 seconds.The number of ICs having cracks were measured. Ten samples were testedfor each resin.

Reference 1

(1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative-1

In a 2-liter four-necked flask with a thermometer, a stirrer, and acondenser, 244.4 g (2.0 mol) of 2,6-xylenol (hereinafter referred to as26XY) and 193.8 g (1.0 mol) of a 40.5% aqueous solution ofchloroacetaldehyde were added to and dissolved in 376 g of acetic acidwith stirring, and the reaction solution was then cooled to 5° C. Asolution prepared by mixing 122 g (1.2 mol) of concentrated sulfuricacid with 84 g of acetic acid was added dropwise to the reaction mixtureat 5° C. over 3 hours. The reaction mixture was then maintained at theconstant temperature of 25° C. for 6 hours, and stirred overnight atambient temperature. The reaction mixture was again cooled to 5° C., anddeposited precipitates were filtered off. The precipitates thus obtainedwere washed with 500 g of water six times and dried in vacuo at 40° C.for 8 hours to give 264 g of colorless precipitates (yield: 86.6%)(hereinafter referred to as XYCE). Gel permeation chromatography(hereinafter referred to as GPC: detected with the ultraviolet ray of254 nm) showed that the purity of the product was 98.3%, while infraredabsorption spectrum gave a broad absorption band due to the hydroxylgroup in the vicinity of 3500 cm-1. A fragment of the molecularweight=304 was observed by mass spectrometry.

(2) Synthesis of stilbene bisphenol-1

In a 2-liter ((liter)) four-necked flask with a thermometer, a stirrer,and a condenser, 225.6 g of XYCE obtained in the above process (1) wasdissolved with stirring in 451.2 g of methanol under nitrogenatmosphere. After 91.9 g of a 48.3% aqueous solution of sodium hydroxidewas added dropwise to the solution over 1 hour at the internaltemperature of 30° C., the reaction mixture was heated and reacted for 3hours under reflux of methanol. After the reaction, completedisappearance of the material XYCE was confirmed by high performanceliquid chromatography (hereinafter referred to as LC). The reactionmixture was cooled to 60° C. and neutralized with 37.5 g of concentratedhydrochloric acid. After removal of methanol, 1000 g of warm water wasadded to the reaction mixture, and precipitates thus deposited werefiltered off. The precipitates obtained were washed with water and driedin vacuo at 80° C. for 8 hours to give 192 g of yellow precipitates(yield: 96.7%) (hereinafter referred to as XYSB). GPC showed that thepurity of the product was 98.1%, while infrared absorption spectrum gavea broad absorption band due to the hydroxyl group in the vicinity of3400 cm-1. A fragment of the molecular weight (mw=268) was observed bymass spectrometry.

(3) Synthesis of epoxy resin-1

In a reaction vessel with a thermometer, a stirrer, a dropping funnel,and a columned condenser, 100 g of the material phenol (XYSB) obtainedin the above process (2) was dissolved in 485.6 g of epichlorohydrin and242.8 g of 1,4-dioxane. While the reaction system was kept at 140 torr,61.71 g of a 48.3% aqueous solution of sodium hydroxide was continuouslyadded dropwise over 5 hours at the temperature of 62° C. The reactionproceeded at the fixed temperature of 62° C., while the azeotropicmixture of epichlorohydrin and water was cooled and liquefied and theorganic phase was returned to the reaction system.

After completion of the reaction, unreacted epichlorohydrin and1,4-dioxane were removed by evaporation under reduced pressure. Theglycidyl ether obtained and by-product salts were dissolved in 800 g ofmethyl isobutyl ketone and washed with water for removal of theby-product salts. Subsequent removal of methyl isobutyl ketone at 160°C. under the reduced pressure of 10 torr gave 122.2 g of final product(yield: 86.2%) (hereinafter referred to as XYCC-E).

The product had the purity of 93.0% measured by GPC (detected with adifferential refractometer), the melting point of 151° C., and the epoxyequivalent weight of 198 g/eq. Infrared spectroscopy showed that theabsorption due to the phenolic hydroxyl group disappeared and that theproduct had absorptions of 1240 cm-1 and 915 cm-1 due to the epoxygroup.

Reference 2

(1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative-2

Synthesis was carried out in the same manner as Reference 1 (1), exceptthat 328.5 g (2.0 mol) of 3-methyl-6-t-butylphenol (hereinafter referredto as 3M6B) was used in place of 244.4 g (2.0 mol) of 26XY, to gave 317g of pale purple precipitates (yield: 81.5%) (hereinafter referred to asXMCE-100). GPC (detected with the ultraviolet ray of 254 nm) showed thatthe purity of the product was 87.7%, while infrared absorption spectrumgave a broad absorption band due to the hydroxyl group in the vicinityof 3500 cm-1. A fragment of the molecular weight=389 was observed bymass spectrometry.

(2) Synthesis of stilbene bisphenol-2

Synthesis was carried out in the same manner as Reference 1(2), exceptthat XMCE-100 obtained in the above process (1) of Reference 2 was usedin place of XYCE, to gave 134 g of pale yellow precipitates (yield:94.8%) (hereinafter referred to as XMSB-100). GPC showed that the purityof the product was 93.5%, while infrared absorption spectrum gave abroad absorption band due to the hydroxyl group in the vicinity of 3100cm-1. A fragment of the molecular weight-352 was observed by massspectrometry.

(3) Synthesis of epoxy resin-2

The epoxidation was carried out in the same manner as Reference 1(3),except that XMSB-100 obtained in the above process (2) was used in placeof XYSB, to gave 54.7 g of final product (yield: 36.2%) (hereinafterreferred to as XMCC-100E). The product had the purity of 95.2% measuredby GPC (detected with a differential refractometer), the melting pointof 220 through 224° C., and the epoxy equivalent weight of 230 g/eq.Infrared spectroscopy showed that the absorption due to the phenolichydroxyl group disappeared and that the product had absorptions of 1230cm-1 and 920 cm-1 due to the epoxy group.

Example 1(1)

(1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative-3

Synthesis was carried out in the same manner as Reference 1(1), exceptthat 195.5 g (1.6 mol) of 26XY and 65.7 g (0.4 mol) of 3M6B were used inplace of 244.4 g (2.0 mol) of 26XY, to gave 271 g of pale purpleprecipitates (yield: 84.1%) (hereinafter referred to as XMCE-20). GPC(detected with the ultraviolet ray of 254 nm) showed that the purity ofthe product was 97.7%, while infrared absorption spectrum gave broadabsorption bands due to the hydroxyl group in the vicinity of 3450 cm-1and 3550 cm-1. Fragments of the molecular weight=346 and 304 wereobserved by mass spectrometry. XMCE-100 of Reference 2(1) ((Reference4)) was not observed by LC analysis.

(2) Synthesis of stilbene bisphenol-3

Synthesis was carried out in the same manner as Reference 1(2), exceptthat 144.8 g of XMCE-20 obtained in the above process (1) of Example 1was used in place of XYCE, to gave 124 g of yellow precipitates (yield:96.6%) (hereinafter referred to as XMSB-20). GPC (detected with theultraviolet ray of 254 nm) showed that the purity of the product was97.1%, while infrared absorption spectrum gave a broad absorption banddue to the hydroxyl group in the vicinity of 3400 cm-1. Fragments of themolecular weight=310 and 268 were observed by mass spectrometry.XMSB-100 of Reference 2(2) ((Reference 5)) was not observed by LCanalysis.

(3) Synthesis of epoxy resin-3

The epoxidation was carried out in the same manner as Reference 1(3),except that 99.7 g of XMSB-20 obtained in the above process (2) was usedin place of XYSB, to gave 131 g of final product (yield: 94%)(hereinafter referred to as XMCC-20E).

GPC (detected with a differential refractometer) showed that the purityof the product was 93.6% and the rate of the stilbene epoxy compoundincluding the 26XY residue and the 3M6B residue ((including 26XY and3M6B)) in its molecular structure was 39.6%. The product had the meltingpoint of 110 through 130° C., and the epoxy equivalent weight of 208g/eq. Infrared spectroscopy showed that the absorption due to thephenolic hydroxyl group disappeared and that the product had absorptionsof 1240 cm-1 and 920 cm-1 due to the epoxy group.

Example 2

(1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative-4

Synthesis was carried out in the same manner as Reference 1(1), exceptthat 171.1 g (1.4 mol) of 26XY and 98.6 g (0.6 mol) of 3M6B were used inplace of 244.4 g (2.0 mol) of 26XY, to gave 253 g of pale purpleprecipitates (yield: 76.7%) (hereinafter referred to as XMCE-30). GPC(detected with the ultraviolet ray of 254 nm) showed that the purity ofthe product was 96.0%, while infrared absorption spectrum gave broadabsorption bands due to the hydroxyl group in the vicinity of 3450 cm-1and 3550 cm-1. Fragments of the molecular weight=346 and 304 wereobserved by mass spectrometry. XMCE-100 of Reference 2(1) ((Reference4)) was not observed by LC analysis.

(2) Synthesis of stilbene bisphenol-4

Synthesis was carried out in the same manner as Reference 1(2) exceptthat 122.1 g of XMCE-30 obtained in the above process (1) was used inplace of XYCE, to gave 108 g of yellow precipitates (yield: 99.4%)(hereinafter referred to as XMSB-30). GPC (detected with the ultravioletray of 254 nm) showed that the purity of the product was 93.3%, whileinfrared absorption spectrum gave a broad absorption band due to thehydroxyl group in the vicinity of 3400 cm-1. Fragments of the molecularweight=310 and 268 were observed by mass spectrometry. XMSB-100 ofReference 2(2) was not observed by LC analysis.

(3) Synthesis of epoxy resin-4

The epoxidation was carried out in the same manner as Reference 1(3),except that 95.4 g of XMSB-30 obtained in the above process (2) was usedin place of XYSB, to gave 118 g of final product (yield: 89.5%)(hereinafter referred to as XMCC-30E).

GPC (detected with a differential refractometer) showed that the purityof the product was 86.6% and the rate of the stilbene epoxy compoundincluding the 26XY residue and the 3M6B residue ((including 26XY and3M6B)) in its molecular structure was 53.2%. The product was semisolidat ambient temperature and had the epoxy equivalent weight of 200 g/eq.The melt viscosity was 0.16 poise at 150° C. Infrared spectroscopyshowed that the absorption due to the phenolic hydroxyl groupdisappeared and that the product had absorptions of 1260 cm-1 and 910cm-1 due to the epoxy group.

Example 3

(1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative-5

Synthesis was carried out in the same manner as Reference 1(1), exceptthat 122.2 g (1.0 mol) of 26XY and 164.3 g (1.0 mol) of 3M6B were usedin place of 244.4 g (2.0 mol) of 26XY, to gave 321 g of colorlessprecipitates (yield: 92.5%) (hereinafter referred to as XMCE-50). GPC(detected with the ultraviolet ray of 254 nm) showed that the purity ofthe product was 90.7%, while infrared absorption spectrum gave broadabsorption bands due to the hydroxyl group in the vicinity of 3450 cm-1and 3550 cm-1. Fragments of the molecular weight=346 and 304 and a faintfragment of the molecular weight=389 were observed by mass spectrometry.

(2) Synthesis of stilbene bisphenol-5

Synthesis was carried out in the same manner as Reference 1(2), exceptthat 114.7 g of XMCE-50 obtained in the above process (1) was used inplace of XYCE, to gave 98.5 g of pale brown precipitates (yield: 95.8%)(hereinafter referred to as XMSB-50). GPC (detected with the ultravioletray of 254 nm) showed that the purity of the product was 96.5% and therate of the stilbene compound including the 26XY residue and the 3M6Bresidue ((including 26XY and 3M6B)) in its molecular structure was86.4%. Infrared absorption spectrum gave a broad absorption band due tothe hydroxyl group in the vicinity of 3400 cm-1. Fragments of themolecular weight=310 and 268 and a faint fragment of the molecularweight (mw=352) were observed by mass spectrometry. (3) Purification ofstilbene bisphenol XMSB-50 obtained in the above process (2) of Example3 was recrystallized from toluene. Precipitates thus obtained werewashed with cyclohexane and dried under reduced pressure to yield finebrown precipitates. The purity measured by high performance liquidchromatography (hereinafter referred to as LC) was 99.1%, and theretention time of the fine precipitates measured by LC completelycoincided with the retention time of the stilbene bisphenol includingthe 26XY residue and the 3M6B residue ((including 26XY and 3M6B)) in itsmolecular structure, which was obtained in the process (2) of Example 3.Infrared absorption spectrum gave a broad absorption band due to thehydroxyl group in the vicinity of 3500 cm-1. A fragment of the molecularweight=310 was observed by mass spectrometry.

Melting point: 175 through 179° C.

1H-NMR &D: 1.43 ppm (s, t-butyl group, 9H) 2.27 ppm (s, Ar--CH3, 6H)2.33 ppm (s, Ar--CH3, 3H) 4.77 ppm (brs, hydroxyl group, 2H) 6.5-7.5 ppm(m, Ar--H, --CH═CH--, 6H)

(4) Synthesis of epoxy resin-5

The epoxidation was carried out in the same manner as Reference 1(3),except that 99.7 g of XMSB-50 obtained in the above process (2) was usedin place of XYSB, to gave 131 g of final product (yield: 94%)(hereinafter referred to as XMCC-50E). GPC (detected with a differentialrefractometer) showed that the purity of the product was 93.5% and therate of the stilbene epoxy compound including the 26XY residue and the3M6B residue in its molecular structure was 80.5%. The product had themelting point of 45° C., the epoxy equivalent weight of 226 g/eq, andthe melt viscosity of 0.2 poise at 150° C. Infrared spectroscopy showedthat the absorption due to the phenolic hydroxyl group disappeared andthat the product had absorptions of 1260 cm-1 and 920 cm-1 due to theepoxy group.

(5) Synthesis of epoxy resin-6

The epoxidation was carried out in the same manner as Reference 1(3),except that 38.8 g of the recrystallized product obtained in the aboveprocess (3) of Example 3 was used in place of XYSB, to gave 50.2 g ofpale yellow viscous liquid substance (yield: 95%). The purity measuredby LC was 94.2% for the stilbene epoxy compound including the 26XYresidue and the 3M6B residue ((including 26XY and 3M6B)) in itsmolecular structure. Infrared spectroscopy showed that the absorptiondue to the phenolic hydroxyl group disappeared and that the product hadabsorptions of 1260 cm-1 and 910 cm-1 due to the epoxy group.*1H-NMR &D:1.42 ppm (s, t-butyl group, 9H) 2.32 ppm (s, Ar-CH3, 6H) 2.38 ppm (s,Ar-CH3, 3H) 2.7-3.0 ppm (m, epoxy-CH2, 4H) 3.4 ppm (m, epoxy-CH, 2H)3.7-4.3 ppm (m, --OCH2, 4H) 6.6-7.5 ppm (m, Ar--H, --CH═CH--, 6H)

Example 4

(1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative-6

Synthesis was carried out in the same manner as Reference 1(1), exceptthat 91.7 g (0.75 mol) of 26XY and 205.4 g ((164.3 g)) (1.25 mol) of3M6B were used in place of 244.4 g (2.0 mol) of 26XY, to gave 315 g ofpale purple precipitates (yield: 88.0%) (hereinafter referred to asXMCE-62.5). GPC (detected with the ultraviolet ray of 254 nm) showedthat the purity of the product was 94.4%, while infrared absorptionspectrum gave broad absorption bands due to the hydroxyl group in thevicinity of 3450 cm-1 and 3550 cm-1. Fragments of the molecularweight=346, 389, and 304 were observed by mass spectrometry.

(2) Synthesis of stilbene bisphenol-6

Synthesis was carried out in the same manner as Reference 1(2), exceptthat 121.1 g of XMCE-62.5 obtained in the above process (1) was used inplace of XYCE, to gave 103 g of pale brown precipitates (yield: 94.7%)(hereinafter referred to as XMSB-62.5). GPC (detected with theultraviolet ray of 254 nm) showed that the purity of the product was92.0%, while infrared absorption spectrum gave a broad absorption banddue to the hydroxyl group in the vicinity of 3500 cm-1. Fragments of themolecular weight (wm=310, 268, and 352) were observed by massspectrometry.

(3) Synthesis of epoxy resin-7

The epoxidation was carried out in the same manner as Reference 1(3),except that 80.3 g of XMSB-62.5 obtained in the above process (2) ofExample 4 was used in place of XYSB, to gave 95.2 g of final product(yield: 87.9%) (hereinafter referred to as XMCC-62.5E). GPC (detectedwith a differential refractometer) showed that the purity of the productwas 85.8% and the rate of the stilbene epoxy compound including the 26XYresidue and the 3M6B residue ((including 26XY and 3M6B)) in itsmolecular structure was 71.0%. The product had the melting point of 105through 125° C., the epoxy equivalent weight of 230 g/eq, and the meltviscosity of 0.4 poise at 150° C. Infrared spectroscopy showed that theabsorption due to the phenolic hydroxyl group disappeared and that theproduct had absorptions of 1260 cm-1 and 915 cm-1 due to the epoxygroup.

Example 5

This Example concerns a test for the solubility of epoxy resins insolvent.

Solubility of the epoxy resins obtained in Examples 1, 2, 3, and 4 andReferences 1 and 2 (XMCC-20E, XMCC-30E, XMCC-50E, XMCC-62.5E, XMCC-100E,XYCC-E) was measured by adding 80 parts by weight of methyl isobutylketone to 20 parts by weight of each epoxy resin and heating eachsolution to 80° C. As for the epoxy resins obtained in References 1 and2, solubility was also measured when 10 parts by weight of each epoxyresin was mixed with 80 parts by weight of methyl isobutyl ketone.

The results of measurement are shown in Table 1, where open circles andcrosses represent `dissolved` and `not dissolved`, respectively. Meltingpoints of the respective epoxy resins are also given in Table 1.

                  TABLE 1    ______________________________________    Epoxy Resins    Melting Point                                Solubility    ______________________________________    XMCC-20E        110-130° C.                                ◯    XMCC-30E        Semisolid at room                                ◯                    temperature    XMCC-50E        45° C.                                ◯    XMCC-62.5E      105-125° C.                                ◯    XMCC-100E       220-224° C.                                X    XYCC-E          151° C.                                X    XMCC-100E/XYCC-E                    151-160° C.                                X    ______________________________________

Reference 3

(1) Synthesis of 1,1-bis(hydroxyphenyl)-2-chloroethane derivative-7

In a 2-liter four-necked flask with a thermometer, a stirrer, and acondenser, 244.4 g (2.0 mol) of 2,6-xylenol (hereinafter referred to as26XY) and 124.5 g (1.0 mol) of chloroacetaldehyde dimethylacetal wereadded to and dissolved in 376 g of acetic acid with stirring, and thereaction solution was then cooled to 5° C. A solution prepared by mixing122 g (1.2 mol) of concentrated sulfuric acid with 84 g of acetic acidwas added dropwise to the reaction solution at 10° C. over 3 hours. Thereaction system was then maintained at the constant temperature of 25°C. for 6 hours, and stirred overnight at ambient temperature. Thereaction system was again cooled to 5° C., and deposited precipitateswere filtered off. The precipitates thus obtained were washed with 500 gof water six times and dried in vacuo at 40° C. for 8 hours to give 268g of pale purple precipitates.

(2) Synthesis of stilbene bisphenol-7

After 245.2 g of an 48.3% aqueous solution of sodium hydroxide and 552 gof N-methylpyrrolidone were placed in a 2-liter four-necked flask with athermometer, a stirrer, and a condenser, the atmosphere in the flask wasreplaced with nitrogen. The solution was heated to 140° C. under thenitrogen encapsulating condition. A solution mixture prepared by mixing225.6 g of the phenol intermediate obtained in the above process (1) ofReference 3 ((Reference 3)) with 676 g of N-methylpyrrolidone was addeddropwise to the heated solution at 140° C. over 1.5 hours and maintainedat the same temperature for 2 hours. The reaction system was cooled to60° C. and neutralized with 226 g of concentrated hydrochloric acid.After removal of the solvent under reduced pressure, 1000 g ofion-exchanged water was added to the reaction mixture, and precipitatesthus deposited were filtered off. The precipitates obtained were washedwith ion-exchanged water three times and dried in vacuo at 80° C. for 8hours to give 190 g of yellow precipitates.

(3) Synthesis of epoxy resin-8

In a reaction vessel with a thermometer, a stirrer, a dropping funnel,and a columned condenser, 100 g of the material phenol obtained in theabove process (2) of Reference 3 ((Reference 3)) was dissolved in 485.6g of epichlorohydrin and 243.1 g of dimethyl sulfoxide. While thereaction system was kept at 43 torr, 61.71 g of a 48.3% aqueous solutionof sodium hydroxide was continuously added dropwise over 5 hours at thetemperature of 48° C. The reaction proceeded at the fixed temperature of48° C., while the azeotropic mixture of epichlorohydrin and water wascooled and liquefied and the organic phase was returned to the reactionsystem.

After completion of the reaction, unreacted epichlorohydrin was removedby evaporation under reduced pressure. By-product salts and the glycidylether including dimethyl sulfoxide thus obtained were dissolved in 644 gof methyl isobutyl ketone and washed with water for removal of theby-product salts and dimethyl sulfoxide. Subsequent removal of methylisobutyl ketone at 160° C. under the reduced pressure of 10 torr gave afinal product (hereinafter referred to as XYCC-E). The product had themelting point of 151° C., the epoxy equivalent weight of 198 g/eq, andthe hydrolytic chlorine of 170 ppm.

Example 6

Synthesis of epoxy resin-9

An intermediate and then a material phenol were obtained in the samemanner as Reference 3, except that 195.5 g (1.6 mol) of 26XY and 65.7 g(0.4 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, andthe material phenol was epoxidized according to the process of Reference3 to yield a final product (hereinafter referred to as XMCC-20E).

The product had the melting point of 110 to 130° C., the epoxyequivalent weight of 208 g/eq, and the hydrolytic chlorine of 170 ppm.The melt viscosity was 0.1 poise at 150° C.

Example 7

Synthesis of epoxy resin-10

An intermediate and then a material phenol were obtained in the samemanner as Reference 3, except that 171.1 g (1.4 mol) of 26XY and 98.6 g(0.6 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, andthe material phenol was epoxidized according to the process of Reference3 to yield a final product (hereinafter referred to as XMCC-30E).

The product was semisolid at room temperature and had the epoxyequivalent weight of 200 g/eq and the hydrolytic chlorine of 190 ppm.The melt viscosity was 0.16 poise at 150° C.

Example 8

Synthesis of epoxy resin-11

An intermediate and then a material phenol were obtained in the samemanner as Reference 3, except that 122.2 g (1.0 mol) of 26XY and 164.3 g(1.0 mol) of 3M6B were used in place of 244.4 g (2.0 mol) of 26XY, andthe material phenol was epoxidized according to the process of Reference3 ((Reference 4)) to yield a final product (hereinafter referred to asXMCC-50E).

The product had the melting point of 45° C., the epoxy equivalent weightof 226 g/eq, and the hydrolytic chlorine of 170 ppm. The melt viscositywas 0.2 poise at 150° C.

Example 9

Synthesis of epoxy resin-12

An intermediate and then a material phenol were obtained in the samemanner as Reference 3, except that 91.7 g (0.75 mol) of 26XY and 205.4 g((164.3 g)) (1.25 mol) of 3M6B were used in place of 244.4 g (2.0 mol)of 26XY, and the material phenol was epoxidized according to the processof Reference 3 ((Reference 4)) to yield a final product (hereinafterreferred to as XMCC-62.5E). The product had the melting point of 105 to125° C., the epoxy equivalent weight of 230 g/eq, and the hydrolyticchlorine of 180 ppm. The melt viscosity was 0.4 poise at 150° C.

Example 10

Synthesis of epoxy resin-13

An intermediate and then a material phenol were obtained in the samemanner as Reference 3, except that 328.5 g (2.0 mol) of 3M6B was used inplace of 244.4 g (2.0 mol) of 26XY, and the material phenol wasepoxidized according to the process of Reference 3 ((Reference 4)) toyield a final product (hereinafter referred to as XMCC-100E).

The product had the melting point of 220 to 224° C., the epoxyequivalent weight of 230 g/eq, and the hydrolytic chlorine of 130 ppm.((hereinafter referred to as XMCC-100E)).

Examples 11-14 and Controls 1-3

Each of the glycidyl ethers obtained in Reference 3 and Examples 6through 10 ((References 6 through 10)) or a commercially availableglycidyl ether of 4,4'-dihydroxy-3,3',5,5'-tetramethylbiphenyl(manufactured by SUMITOMO CHEMICAL CO., LTD.) was mixed with phenolnovolak (trade name: Tamanol 758 manufactured by Arakawa ChemicalIndustries Co., Ltd.) working as a curing agent, triphenylphosphineworking as a curing accelerator, molten silica (the grade andcomposition are shown below) as fillers, and carnauba wax and a couplingagent (trade name: SH-6040 manufactured by Toray Dowcorning SiliconeCo., Ltd.) as mold parting agents, according to the composition (g)shown in Table 2. Each composition was subjected to milling underapplication of heat and subsequently to transfer molding.

Cured objects were obtained after the 5-hour post curing process in a180° C. oven. Physical properties of the cured objects were measured.The results of measurement are shown in Table 2. Grade and compositionof molten silica.

1. FS-20: ground silica (average particle diameter: 5.6 m) by DENKIKAKAGU KOGYO K.K.

2. Admafine SO-C2: spherical silica (average particle diameter: 0.4 m)by Admatec Co., Ltd.

3. Silstar MK-06: spherical silica (average particle diameter: 4.9 m) byNippon Chemical Industrial Co., Ltd.

4. Excelica SE40: spherical silica (average particle diameter: 40.4 m)by Tokuyama Corp.

A mixture containing 10% by weight of silica 1, 10.8% by weight ofsilica 2, 18% by weight of silica 3, and 61.2% by weight by silica 4 wasused as fillers in Table 2.

                                      TABLE 2    __________________________________________________________________________                Example 11                      Example 12                            Example 13                                  Example 14                                        Control 1                                             Control 2                                                   Control 3    __________________________________________________________________________    Composition (parts by wt)    XMCC-20E    100   --    --    --    --   --    --    XMCC-30E    --    100   --    --    --   --    --    XMCC-50E    --    --    100   --    --   --    --    XMCC-62.5E  --    --    --    100   --   --    --    XYCC-E      --    --    --    --    100  --    --    XMCC-100E   --    --    --    --    --   100   --    Biphenyl epoxy                --    --    --    --    --   --    100    Phenol novolak                51    52    46.9  46    53.6 45.7  55.5    Triphenylphosphine                1.5   1.5   1.5   1.5   1.5  1.5   1.5    Fillers     1359  1370  1322  1314  1382.3                                             1311.3                                                   1400    Carnauba wax                3.28  3.31  3.19  3.17  3.34 3.17  3.38    Silane coupling agent                4.4   4.41  4.25  4.23  4.44 4.23  4.5    SH-6040    Working properties                ◯                      ◯                            ◯                                  ◯                                        X    X     ◯    Spiral flow            inch                36    39    31    32    36   Poor flow                                                   47    Barcol hardness            --  81    83    81    80    84   properties                                                   83    Glass transition            ° C.                152   145   156   147   138  and   135    temperature                              incapable    Bending strength            kg/cm.sup.2                2.22  1.8   1.57  1.59  2.1  of preparing                                                   1.66    Bending modulus            kg/cm.sup.2                166   141   138   131   179  test pieces                                                   189    Water absorption    72 hours            %   0.169 0.166 0.195 0.182 0.156      0.183    168 hours            %   0.207 0.202 0.213 0.21  0.194      0.224    336 hours            %   0.205 0.23  0.22  0.227 0.261      0.25    Solder cracking    72 hours            %   0     0     0     0     0          0    168 hours            %   0     0     0     0     20         20    336 hours            %   0     0     0     0     60         80    __________________________________________________________________________

Example 15

Synthesis of epoxy resin-14

An intermediate XMCE-20 and then a material phenol XMSB-20 were ((Anintermediate XMCE-20 was)) obtained in the same manner as the processes(1) and (2) of Reference 3 ((Reference 3(1))), except that 195.5 g (1.6mol) of 26XY and 65.7 g (0.4 mol) of 3M6B were used in place of 244.4 g(2.0 mol) of 26XY. The process (3) of Reference 3 was repeated using80.8 g of the material phenol XMSB-20 ((the intermediate XMCE-20 insteadof XMSB-20)) and 62.36 g, instead of 61.71g, of the 48.3% aqueoussolution of sodium hydroxide, to give 96.4 g of final product (yield:97%) (hereinafter referred to as XMCC-20E).

GPC (detected with a differential refractometer) showed that the purityof the product was 93.2% and the rate of the stilbene epoxy compoundincluding the 26XY residue and the 3M6B residue ((26XY and 3M6B)) in itsmolecular structure was 39.5%. The product had the melting point of 110through 130° C. and the epoxy equivalent weight of 208 g/eq. Infraredspectroscopy showed that the absorption due to the phenolic hydroxylgroup disappeared and that the product had absorptions of 1240 cm-1 and920 cm-1 due to the epoxy group. The hydrolytic chlorine was 280 ppm.

Compared with the conventional stilbene epoxy resin compositions, thestilbene epoxy resin composition of the present invention has betterworking and molding properties and advantages in the handling process.The stilbene epoxy resin composition of the present invention has lowhygroscopicity and excellent heat resistance and is favorably used asmaterial for encapsulating electronic parts. Resin-encapsulatedsemiconductor devices utilizing the resin composition of the presentinvention have high resistance against solder cracking and do not causepackage cracks even after the long-time water absorption. The presentinvention accordingly provides a encapsulating material having highreliability without damaging the molding conditions and workingproperties of the conventional encapsulating materials.

What is claimed is:
 1. A stilbene epoxy resin having a melting point ofnot higher than 150° C. which is represented by the general formula (2),in which two different aryl groups are bound to a carbon--carbon doublebond, ##STR7## wherein R₁ through R₈ Independently represent acyclic orcyclic alkyl groups having 1 through 6 carbon atoms, or hydrogen atoms.2. An epoxy resin mixture having a melting point of not higher than 150°C., sold epoxy resin mixture comprising a stilbene epoxy resin asrecited in claim 1, and a stilbene epoxy resin represented by thegeneral formula (4) in which two identical aryl groups are bound to acarbon--carbon double bond, ##STR8## wherein R₉ through R₁₂independently represent acyclic or cyclic alkyl groups having 1 through6 carbon atoms, or hydrogen atoms.
 3. An epoxy resin in accordance withclaim 1 , wherein R₁ represents a t-butyl group, and R₅ through R₈represent acyclic alkyl groups other than t-butyl group, cyclic alkylgroups, or hydrogen atoms in the general formula (2) given above.
 4. Anepoxy resin mixture in accordance with claim 2, said epoxy resin mixturehaving a melt viscosity of not greater than 1 poise at 150° C.
 5. Amethod of preparing an epoxy resin mixture in accordance with claim 2,said method comprising the steps of: subjecting a1,1-bis(hydroxyphenyl)-2-chloroethane derivative, which is obtained by areaction of two or more phenols with chloroacetaldehyde in the presenceof an acid substance, to a dehydrochlorination reaction in the presenceof a basic substance to yield a dihydroxystilbene derivative; andreacting said dihydroxystilbene derivative with an epihalohydrin in thepresence of a basic substance.
 6. A method of preparing an epoxy resinmixture in accordance with claim 2, said method comprising the stepsofallowing a 1,1-bis(hydroxyphenyl)-2-chloroethane derivative, which isobtained by a reaction of two or more phenols with chloroacetaldehyde inthe presence of an acid substance, to react with an epihalohydrin in thepresence of a basic substance.
 7. A method in accordance with eitherclaim 5 or 6 or, wherein said phenols comprise two or more phenolsselected from the group consisting of 2,6-xylenol, 2,4-xylenol,3-methyl-6-t-butylphenol, and 2-methyl-6-t-butylphenol.
 8. A method inaccordance with claim 7, wherein said phenols comprise a mixture of2,6-xylenol and 3-methyl-6-t-butylphenol.
 9. An epoxy resin compositioncomprising:(A) a stilbene epoxy resin in accordance with claim 1, and(B) a phenolic epoxy curing agent.
 10. An epoxy resin composition inaccordance with claim 9, wherein said stilbene epoxy resin has a meltingpoint of not greater than 150° C.
 11. An epoxy resin composition inaccordance with claim 9, wherein said stilbene epoxy resin representedby the general formula (2) comprises at least one resin selected fromthe group consisting of glycidyl ether compounds of3-t-butyl-2,4'-dihydroxy-3',5',6-trimethylstilbene and3-t-butyl-4,4'-dihydroxy-3',5',6-trimethylstilbene; and said compositionfurther comprises a stilbene epoxy resin selected from the groupconsisting of glycidyl ether compounds of4,4'-dihydroxy-3,3',5,5'-tetramethylstilbene,4,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene,2,2'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene, and2,4'-dihydroxy-3,3'-di-t-butyl-6,6'-dimethylstilbene.
 12. An epoxy resincomposition in accordance with claim 9, wherein the curing agentcomprises a polyphenol resin having a melt viscosity of 1.5 poise orless at 150° C.
 13. An epoxy resin composition in accordance with claim12, wherein the polyphenol resin is represented by the general formula(5) ##STR9## wherein X represents single bond or methylene, Q representsphenylene or a divalent alicyclic moiety derived from dicyclopentadieneor limonene, and n represents an integer of 1 to
 20. 14. An epoxy resincomposition in accordance with claim 12, wherein the curing agentfurther comprises a phenol novolak.
 15. An epoxy resin composition inaccordance with any one of claims 9, 10, 7, 12, 13, or 14, wherein saidepoxy resin further comprises (C) inorganic fillers.
 16. Aresin-encapsulated semiconductor device manufactured by encapsulating asemiconductor element with an epoxy resin composition in accordance withclaim
 15. 17. An epoxy resin in accordance with claim 1, wherein saidstilbene epoxy resin represented by the general formula (2) comprises atleast one resin selected from the group consisting of glycidyl ethercompounds of 3-t-butyl-2,4'-dihydroxy-3',5',6-trimethylstilbene and3-t-butyl-4,4'-dihydroxy-3',5',6-trimethylstilbene.
 18. An epoxy resinin accordance with claim 1, wherein said stilbene epoxy resinrepresented by the general formula (2) comprises at least one resinobtained by glycidyl etherification of a compound selected from thegroup consisting of 3-t-butyl-4,4'-dihydroxy-3'-methyl-stilbene,3-t-butyl-4,4'-dihydroxy-5,3'-dimethyl-stilbene,3-t-butyl-4,4'-dihydroxy-3',6-dimethylstilbene,3-t-butyl-4,4'-dihydroxy-5-ethyl-3'-methylstilbene,3-t-butyl-4,4'-dihydroxy-3'-methyl-5-propylstilbene,3-t-butyl-4,4'-dihydroxy-5-butyl-3'-methyl-stilbene,3-t-butyl-4,4'-dihydroxy-5-amyl-3'-methylstilbene,3-t-butyl-4,4'-dihydroxy-5-hexyl-3'-methylstilbene,3-t-butyl-4,4'-dihydroxy-5-cyclohexyl-3'-methylstilbene,3-t-butyl-4,4'-dihydroxy-3',5,5'-trimethyl-stilbene,3-t-butyl-2,4'-dihydroxy-3',5',6-trimethylstilbene,3-t-butyl-4,4'-dihydroxy-3',5',6-trimethylstilbene,3-t-butyl-4,4'-dihydroxy-3',5-dimethyl-5'-propylstilbene and3-t-butyl-4,4'-dihydroxy-3',6-dimethyl-5'-propylstilbene.
 19. An epoxyresin in accordance with claim 1, wherein R₅ through R₈ representacrylic alkyl groups other than a t-butyl group, cyclic alkyl groups, orhydrogen atoms in the general formula (2) given above.
 20. An epoxyresin in accordance with claim 1, wherein R¹ represents a t-butyl group.21. An epoxy resin in accordance with claim 1, wherein R¹ represents anacyclic or cyclic alkyl group having 1 to 6 carbon atoms, and R₅ throughR₈ represent cyclic or acyclic alkyl groups having 1 to 6 carbon atomswhich are different than R¹.
 22. An epoxy resin composition according toclaim 9, wherein said stilbene resin is in accordance with claim
 2. 23.An epoxy resin composition in accordance with claim 22, wherein saidepoxy resin further comprises (C) inorganic fillers.
 24. Aresin-encapsulated semiconductor device manufactured by encapsulating asemiconductor element with an epoxy resin composition in accordance withclaim 23.